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The CFTR gene codes for an ABC transporter-class ion channel protein that conducts chloride [8] and bicarbonate ions across epithelial cell membranes. Mutations of the CFTR gene affecting anion channel function lead to dysregulation of epithelial lining fluid (mucus) transport in the lung, pancreas and other organs, resulting in cystic fibrosis.
For sweat to be produced with the proper concentrations of sodium and chloride, sodium channels and chloride channels (CFTRs) must work properly. In cystic fibrosis, the CFTR chloride channel is defective, and does not allow chloride to be reabsorbed into sweat duct cells.
The CFTR channels are therefore critical to determining transepithelial salt transport, fluid flow, and concentrations of ions. CFTR chloride channels have important roles in various aspects of the human body, such as in fluid and electrolyte secretion within the intestines, pancreas, and sweat glands.
Mammals have multiple isoforms (at least 6 different gene products plus splice variants) of epithelial chloride channel proteins, catalogued into the Chloride channel accessory (CLCA) family. [8] The first member of this family to be characterized was a respiratory epithelium, Ca 2+ -regulated, chloride channel protein isolated from bovine ...
Ivacaftor is a selective small-molecule potentiator of the CFTR protein that increases the protein's ability to open chloride channels. [ 23 ] [ 24 ] Its effectiveness is highly dependent on the amount of CFTR protein at the cell surface and the responsiveness of the mutant CFTR protein. [ 25 ]
However, a small portion of patients with cystic fibrosis, especially those with "mild" mutations of the cystic fibrosis transmembrane regulator (CFTR) ion channel, have near-normal sweat tests. In these cases, a useful diagnostic adjunct involves measuring the nasal transepithelial potential difference (i.e. the charge on the respiratory ...
CFTR is a transmembrane channel responsible for chloride transport and defects in this protein cause cystic fibrosis, partly through upregulation of the ENaC channel in the absence of functional CFTR. In the airways, CFTR allows for the secretion of chloride, and sodium ions and water follow passively. However, in the absence of functional CFTR ...
The minimum physiological requirement for sodium is between 115 and 500 mg per day depending on sweating due to physical activity, and whether the person is adapted to the climate. [5] Sodium chloride is the principal source of sodium in the diet, and is used as seasoning and preservative, such as for pickling and jerky ; most of it comes from ...